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Adds a faster counter

This commit is contained in:
Stephen McQuay (smcquay) 2017-12-15 11:03:24 -08:00
parent 661e31bf84
commit ae6939214c
No known key found for this signature in database
GPG Key ID: 4E4B72F479BA3CE5
2 changed files with 36 additions and 6 deletions
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20
prometheus/counter_test.go
View File

@ -28,11 +28,25 @@ func TestCounterAdd(t *testing.T) {
ConstLabels: Labels{"a": "1", "b": "2"},
}).(*counter)
counter.Inc()
if expected, got := 1., math.Float64frombits(counter.valBits); expected != got {
if expected, got := 0.0, math.Float64frombits(counter.valBits); expected != got {
t.Errorf("Expected %f, got %f.", expected, got)
}
if expected, got := int64(1), counter.valInt; expected != got {
t.Errorf("Expected %f, got %f.", expected, got)
}
counter.Add(42)
if expected, got := 43., math.Float64frombits(counter.valBits); expected != got {
if expected, got := 0.0, math.Float64frombits(counter.valBits); expected != got {
t.Errorf("Expected %f, got %f.", expected, got)
}
if expected, got := int64(43), counter.valInt; expected != got {
t.Errorf("Expected %f, got %f.", expected, got)
}
counter.Add(24.42)
if expected, got := 24.42, math.Float64frombits(counter.valBits); expected != got {
t.Errorf("Expected %f, got %f.", expected, got)
}
if expected, got := int64(43), counter.valInt; expected != got {
t.Errorf("Expected %f, got %f.", expected, got)
}
@ -43,7 +57,7 @@ func TestCounterAdd(t *testing.T) {
m := &dto.Metric{}
counter.Write(m)
if expected, got := `label:<name:"a" value:"1" > label:<name:"b" value:"2" > counter:<value:43 > `, m.String(); expected != got {
if expected, got := `label:<name:"a" value:"1" > label:<name:"b" value:"2" > counter:<value:67.42 > `, m.String(); expected != got {
t.Errorf("expected %q, got %q", expected, got)
}
}

22
prometheus/value.go
View File

@ -46,6 +46,9 @@ type value struct {
// operations. http://golang.org/pkg/sync/atomic/#pkg-note-BUG
valBits uint64
// valInt is used to store values that are exact integers
valInt int64
selfCollector
desc *Desc
@ -82,15 +85,25 @@ func (v *value) SetToCurrentTime() {
v.Set(float64(time.Now().UnixNano()) / 1e9)
}
// add adjusts the underlying int64
func (v *value) add(delta int64) {
atomic.AddInt64(&v.valInt, delta)
}
func (v *value) Inc() {
v.Add(1)
v.add(1)
}
func (v *value) Dec() {
v.Add(-1)
v.add(-1)
}
func (v *value) Add(val float64) {
if math.Trunc(val) == val {
atomic.AddInt64(&v.valInt, int64(val))
return
}
for {
oldBits := atomic.LoadUint64(&v.valBits)
newBits := math.Float64bits(math.Float64frombits(oldBits) + val)
@ -105,7 +118,10 @@ func (v *value) Sub(val float64) {
}
func (v *value) Write(out *dto.Metric) error {
val := math.Float64frombits(atomic.LoadUint64(&v.valBits))
fval := math.Float64frombits(atomic.LoadUint64(&v.valBits))
ival := atomic.LoadInt64(&v.valInt)
val := fval + float64(ival)
return populateMetric(v.valType, val, v.labelPairs, out)
}